This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The study of the folding mechanism of single domain proteins that lack cofactors has reached an advanced stage wherein the sequence of events along the course of refolding after denaturation begins to be understood. In several cases, it has been even possible to describe in detail the energetics, position, and structure of the folding transition states and/or intermediate states involved. In contrast, there are far fewer studies on cofactor-induced folding kinetics, even though a large number of proteins require cofactors for proper folding and/or function. While the effect of cofactor-binding on the structure and stability may differ for different proteins, many polypeptides can only attain a well-folded structure when associated with their respective cofactors.